MEDRADSC 3K03 Lecture Notes - Lecture 18: Quality Control, Pulse-Code Modulation, Hounsfield Scale
6 Jan 2018
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Document Summary
Linearity: refers to the relationship of ct numbers to the linear attenuation coefficients of the object to be imaged. Spatial resolution: need to define a certain amount of lp/mm, mtf complex and time consuming, done by physicist, direct measure faster and simpler, done by technologist, should be done when there are changes to the ct scanner. Laser light accuracy: defines positioning and alignment of laser system, accurate laser light performance critical, specific phantom designed. Laser light should be within 2mm: semi-annually. Radiation dose: done by physicist, uses ctdi phantoms and pencil ionization chambers, calculate ctdi for head, pediatric abdo (5 yo) and adult abdo, compare with establish reference levels that are set by manufacturers. If above, must review protocols and justify: the protocols being used for imaging all of these phantoms are reviewed and discussed. Summary: qa purpose, tests, noise, uniformity, linearity, spatial resolution, contrast resolution, slice thickness, laser light, dose.
